[Patent Literature 1] JP 2012-54830 A (US 2012/0051241 A)
For example, Patent Literature 1 discloses a communication system to wake up the respective communication nodes that are under a sleep mode. The communication system uses a communication frame that contains an activation pattern area and an assignment pattern area. A subject communication node, which is any one of the plurality of communication nodes, includes a transceiver with an activation frame detection section. When determining a received communication frame as an activation frame directed at the subject communication node itself, the activation frame detection section generates a wake-up signal, thereby permitting a microcomputer of the subject communication node to execute a wake-up process. The received communication frame is determined as an activation frame directed at the subject communication node itself under condition that (i) the activation pattern area contains an activation-used ID having an area length up to a border point, the area length being longer than an activation length, and, simultaneously, (ii) the assignment pattern area contains an assignment code assigned to the subject communication node.
The above activation frame detection section can distinguish whether the received communication frame is an individual or unique activation frame for waking up the subject communication node, even without the use of a highly precise clock source nor a protocol controller. This configuration can reduce the electricity consumption of the subject communication node under the sleep mode, even though the activation frame detection section is constantly under the activated state.
However, the technology disclosed in Patent Literature 1 requires all communication nodes each necessary for wake-up to have the above activation frame detection section. This makes the configuration of each communication node complicated, thereby inevitably increasing costs.